Fabrication And Mechanical Performances Of Graphene/Hydroxyapatite Composites

Graphene, or reduced-graphene oxide (RGO), two dimensional (2-D) monolayer or multilayer of sp2-bonded carbon sheets, has a potential application in electron, biology and composites fileds for its excellent electrical,optical,thermal and mechanical properties. With the discovery of graphene in vivo/vitro, it is hopefully to apply graphene in the biological fields. Now the reports about application of graphene in the tissue engineering scaffolds, bone tissue regeneration and implantation is rarely reported, and mostly of them are about the Graphene/Hydroxyapatite(RGO/HA) composites. However, there exist some problems in these reports, such as low crystallity of HA, the aggregation of RGO, the harmful reductants used in the fabrication et al.This thesis mostly research the fabrication route of RGO/HA composites, and the Physicochemical characterization of composites, espectivelly focus on the phenomenon of low crystallinity of HA and the use of toxtic reductants in the existing fabrication route:This thesis fabricate the Graphene oxide(GO) by modified Hummers method firstly, and the results show that GO sheets are full of oxygen functional groups, its C/O ratio is2.1, and show charge negative in the aqueous solution, which make it disperse in aqueous solution uniformly. The RGO sheets reduced from GO via hydrothermal route, for its residual oxygen functional groups especially carboxyl group on its sheets, make it disperse in aqueous solution uniformly too.This thesis fabricates RGO/HA composites via hydrothermal route, study the mechanism of RGO/HA composites and the influence of pH modifiers(urea, NaOH and ammonia) to the composites. The results showed that RGO/HA composites could be formed by these three pH modifier, and HA in the three composites have a high crystallinty. But there exist some phenomenons that preferred orientation of HA, hudge difference of the morphology of composites. Meanwhile this thesis also study the influence of GO content to mechanical properties of composites, compared to the elastic modulus and compress strength of pure HA, that of RGO/HA composites with3wt%GO increase204%and298%.This thesis fabricates RGO/HA self-assembly hydrogel via hydrothermal route, and study the formation mechanism by the product obtained from different react time, meanwhile, this thesis also researches the influence of GO/HA mass ratio to the mechanical properties of hydrogel, the results show the add of HA decreases the elastic modulus and compress strength of hydrogel.